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author | Dave Chinner <dchinner@redhat.com> | 2015-06-04 09:18:18 +1000 |
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committer | Dave Chinner <david@fromorbit.com> | 2015-06-04 09:18:18 +1000 |
commit | ce5c5d554dc47a4fb4360c84b72231fea081e7a0 (patch) | |
tree | 93915bd75b2061c36dfbffd10a8efd22e0d7282b /fs/dax.c | |
parent | e842f2903908934187af7232fb5b21da527d1757 (diff) | |
download | linux-ce5c5d554dc47a4fb4360c84b72231fea081e7a0.tar.gz |
dax: expose __dax_fault for filesystems with locking constraints
Some filesystems cannot call dax_fault() directly because they have different locking and/or allocation constraints in the page fault IO path. To handle this, we need to follow the same model as the generic block_page_mkwrite code, where the internals are exposed via __block_page_mkwrite() so that filesystems can wrap the correct locking and operations around the outside. This is loosely based on a patch originally from Matthew Willcox. Unlike the original patch, it does not change ext4 code, error returns or unwritten extent conversion handling. It also adds a __dax_mkwrite() wrapper for .page_mkwrite implementations to do the right thing, too. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Dave Chinner <david@fromorbit.com>
Diffstat (limited to 'fs/dax.c')
-rw-r--r-- | fs/dax.c | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/fs/dax.c b/fs/dax.c index 4bb5b7cd5dfd..99b5fbc38992 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -312,7 +312,17 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh, return error; } -static int do_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, +/** + * __dax_fault - handle a page fault on a DAX file + * @vma: The virtual memory area where the fault occurred + * @vmf: The description of the fault + * @get_block: The filesystem method used to translate file offsets to blocks + * + * When a page fault occurs, filesystems may call this helper in their + * fault handler for DAX files. __dax_fault() assumes the caller has done all + * the necessary locking for the page fault to proceed successfully. + */ +int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, get_block_t get_block, dax_iodone_t complete_unwritten) { struct file *file = vma->vm_file; @@ -443,6 +453,7 @@ static int do_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, } goto out; } +EXPORT_SYMBOL(__dax_fault); /** * dax_fault - handle a page fault on a DAX file @@ -463,7 +474,7 @@ int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, sb_start_pagefault(sb); file_update_time(vma->vm_file); } - result = do_dax_fault(vma, vmf, get_block, complete_unwritten); + result = __dax_fault(vma, vmf, get_block, complete_unwritten); if (vmf->flags & FAULT_FLAG_WRITE) sb_end_pagefault(sb); |